Riding lawn equipment, compact tractors, commercial mowers, and golf and turf mowing equipment are typically powered by internal combustion engines. These machines include engine speed controls that an operator may use to regulate the rate at which fuel is supplied to the engine. The engine speed controls may include a lever near the operator's seat, and the lever may be connected to a push/pull cable or mechanical linkage that controls the throttle position of a gasoline engine, or the fuel injectors on a diesel engine. A governor may be provided between the cable or linkage and the throttle or fuel injectors. The engine speed, or rotational rate of the engine, may be proportional to the position of the engine speed controls depending on the load.
In the past, many grass mowing machines also have included infinitely variable hydrostatic transmissions to control direction and the drive ratio of the vehicle. For example, the hydrostatic transmission may be controlled with one or a pair of foot operated pedals. Depressing a foot pedal causes the vehicle to move forward or reverse and, at a given engine speed, the travel speed of the vehicle may be proportional to the distance the pedal is depressed.
Controls for engine speed and the hydrostatic transmission are not linked, but are controlled separately. This adds to the complexity of operating the equipment. To simplify operation, some operators may set the engine speed control so that the engine is at a fast idle, and control vehicle travel speed only with the transmission. As a result, an operator may run the engine at a higher speed than is necessary or desirable. Running the engine at a high speed may waste fuel, and create unnecessary noise and vibration which may be undesirable to the operator and bystanders.
An additional problem with separate controls for the engine speed and hydrostatic transmission occurs when a power take-off (PTO) is engaged to the engine. Mower decks, tillers, and other attachments may be driven by a PTO. These attachments are heavy loads on the engine, and it is important to operate them at a fast engine speed. However, some operators do not properly and sufficiently increase the engine speed when operating attachments.
Accordingly, a simplified control system is needed for an operator to control the engine speed of a lawn and garden tractor, compact tractor, commercial mower, or golf and turf mowing machine. An electronic engine speed control system is needed that, based on the desired vehicle speed, can set an engine speed actuator so that the engine runs at an optimal speed that does not waste fuel or create unnecessary noise and vibration. An electronic engine speed control system is needed that can help assure that attachments and implements driven by the PTO of a lawn and garden tractor are operated at an appropriate and sufficient engine speed.